A mobile phone generally provides a password setting to protect personal information of a user of the mobile phone. The user needs to correctly input a preset password to unlock the screen when using the mobile phone.
A password can consist of number(s) and/or letter(s). Conventionally, the password can be classified as a fixed-length password or an unfixed-length password. If the mobile phone accepts a password of a fixed, specified length, the password is referred to as a fixed-length password. If the mobile phone accepts a password of a variable length in a range, the password is referred to as an unfixed-length password.
Conventionally, to unlock the screen of the mobile phone, the user needs to click, e.g., an “UNLOCK” icon, on the screen after the user inputs the password.